In recent years, a copper-including wiring has begun to be used for a wiring board, for example, a TFT (Thin Film Transistor) substrate. After the wiring is formed on the wiring board, corrosion due to oxidization may occur on the wiring when baking process is carried out in an atmosphere having a particular gas.
In order to prevent such corrosion, JP 4238956 B proposes using a copper wiring and a metal oxide conductor to form a wiring, and covering the copper wiring with the metal oxide conductor.